The present invention addresses the problem of providing a novel drug for the prevention of autoimmune diseases, the suppression of the progression of the symptoms of autoimmune diseases, the suppression of the recurrence of autoimmune diseases, or the treatment of autoimmune diseases. As a result of diligent investigation, the inventors of the present invention have focused on PD-1/CD3 bispecific antibodies as substances that can solve the abovementioned problem and have confirmed that said bispecific antibodies make it possible to achieve pharmaceuticals that reduce the occurrence of the adverse effects known as infusion-related reaction and cytokine release syndrome. In addition, the inventors have confirmed that said bispecific antibodies allow for interaction between PD-1 and its ligand PD-L1 and have discovered that said feature contributes to enhanced and sustained activity.
